teach

---
name: teach
description: Teach a subsystem or change so the reader can reason about it, combining how and why evidence. Use for real understanding rather than summary.
---
# Teach

1. Run the substance of `how` and, when historical rationale matters, `why`.
2. Start with the smallest mental model that predicts behavior.
3. Add one layer at a time: actors/data, control flow, invariants, edge cases, then rationale/tradeoffs.
4. Use tiny diagrams and concrete examples that can be checked against the code.
5. End with a few prediction questions or "what would happen if" cases that test understanding, with answers only when useful.